I've been an AutoCAD/Inventor user for 20+ years, Solidworks for 5, Catia for a miserable 10 years, but only with a specific customer. I tried Pro/E on a student license when in school and I think that is what CREO is now, but I could be wrong. There were some cool features in Pro/E, but also a lot of bad implementation from a usability standpoint, IMO, but current versions might be better.
I just bought Alibre 'Expert' and my initial impression is that it is a 2005 version of parametric CAD vs. the other major players. Having said that, I refuse to 'rent' software, so Autodesk is out and Catia is miserable and crazy expensive, so it is out as well. I waffled a ton on getting a basic version of Solidworks, but given the association with Dassault, I assume Solidworks will migrate to the rental version in the next few years.
It seems that Alibre is pseudo-good, but somewhat shareware/free-ware-ish as far as development in places. My gut feeling is that I can work with that knowing I own the software outright and will be able to work with 10 year old files if that is a concern.
CAD is both fun and it is lame at the same time, IMO.
Sandy